Flavourtech explains how its Rotating Disc Column improves the extraction process


Flavourtech explains how its Rotating Disc Column is helping roasters meet the demand for soluble coffee offerings.

With many coffee roasters seeing the growth of the instant and ready-to- drink (RTD) market and thinking about expanding their product portfolio, Paul Ahn, Sales Manager at global technology manufacturer Flavourtech, says it’s a natural progression to provide a higher quality product.

“Coffee roasters take such pride in their work. To them, it is both an art and science in producing roasted beans full of flavour,” Ahn says. “We are seeing the rise of specialty instant coffee, and as the demand increases, so must production. We can help here by providing a means to do so on a commercial scale and with consistency.”

Ahn says convenience and quality will continue to be driving forces for the coffee industry in 2023, and it will be joined by a continuation towards more natural and healthy products.

“We will continue to help our customers adapt quickly to the changes and help them grow with demand. Our systems are all about capturing the natural flavours from the product itself through a gentle yet efficient process,” he says.

Ahn says Flavourtech, an aroma recovery and extraction specialist, is able to cater for this demand thanks in part to its Rotating Disc Column (RDC).

“The RDC is a continuous extraction device operating closely to plug flow (an idealised flow without any mixing in the axial direction but perfectly in the radial direction). Its function is to hold a slurry flow of solids in liquid for a specified residence time and at a specified temperature so that the transfer of soluble components from the solid particles to the liquid extract is maximised,” says Ahn.

Inside the RDC is a central, vertical drive shaft. Attached to the shaft is a series of rotating baffles. Between each adjacent pair of rotating baffles is a stationary baffle. Slurry is pushed from the bottom of the RDC up through the column, ensuring identical extraction time and consistency.

The RDC can be inserted into Flavourtech’s Integrated Extraction System (IES), a continuous, automated processing line that allows customers to produce premium aromas, extracts, and concentrates for RTD coffee and tea products, as well as soluble coffee and flavour industries.

“This allows a continuous flow of coffee slurry for high temperature extraction. The slurry is exposed to temperatures of between 150° to 195°C for just 20 minutes to enable further hydrolysis to take place. The end result is a premium RTD or soluble product in terms of quality and enhanced aroma at the end of the line. In a traditional process, extraction cells are set at high temperatures and pressure that could last for three to four hours instead of 20 minutes,” Ahn says.

The internal volume of the RDC is determined by the desired product flow rate and holding time and is tailored to customer requirements.

“The RDC allows temperature, pressure, and residence time to be controlled precisely to obtain near identical conditions for all parts of the mixture being processed, ensuring consistency in processing and ultimately, contributing to a superior end product,” says Ahn.

“In contrast to batch tank processing, the RDC’s continuous and automated process means a superior product of higher quality and with consistency.”

Ahn says there are many benefits to this extraction process that allows the manufacturer to capture the unique roast and ground flavours of coffee beans.

“The RDC’s unique design ensures the materials flowing through it are maintained in a continuous, dynamic state, preventing settling and the formation of static pockets,” he says. “The risk of burning and the formation of undesirable burnt notes are greatly reduced as the RDC offers precise control of temperature and with a reduced residence time during the extraction process.”

He says the RDC is ideal as a continuous coffee extraction tank, feeding the extract to the next stage of a process.

“Typically, extraction is conducted batch-wise in large static tanks or cells and so requires a much larger footprint in the factory,” says Ahn.

Normally in the coffee industry, Ahn says flavour is recovered following the high temperature soluble solids extraction process by which point many of coffee’s desirable flavours have already been lost.

“Based on Flavourtech’s 40 years of experience in the flavour industry, we know that the best natural aroma comes from processing the raw material directly in our Spinning Cone Column (SCC), prior to the product being subjected to high temperatures,” he says.

As a result, Flavourtech designed the RDC to allow for high temperature extraction of coffee slurry post SCC aroma capture.

“In Flavourtech’s extraction process, the coffee slurry is first processed through the SCC to capture the natural fresh roast and ground notes. It is then sent to the RDC for extraction of the soluble solids. This means all the fresh coffee notes are preserved and can be added back later in the process to produce instant coffee that smells and tastes like it was freshly brewed,” says Ahn.

Flavourtech originally designed the RDC in the early 2000s with instant coffee producers in mind. The consumption habits of soluble coffee recently, however, would radically shift during the recent pandemic event.

“The demand for soluble coffee has gone up due to more people choosing to work from home,” he says. “Though, they are seeking better quality coffee in terms of flavours, something that is close to the flavours of freshly brewed coffee. We now see a category called ‘specialty instant coffee’ rise quickly.”

The final step in the soluble coffee process is to concentrate the extract before spray or freeze drying the product. Ahn says Flavourtech’s evaporation technique is unique in that the liquid remains in its Centritherm evaporator with a residence time of just one second with low operating temperatures, eliminating the production of burnt flavours in the final product.

“The whole process is continuous, automated, and designed to provide a premium product. With the IES, customers can produce a consistent product, day in day out, with minimal fuss and labour, and maximum flavour that is more in line with the flavour of a freshly brewed espresso,” Ahn says.

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This article was first published in the March/April 2023 edition of Global Coffee Report. Read more HERE.

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